Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758662Ab0GOUwb (ORCPT ); Thu, 15 Jul 2010 16:52:31 -0400 Received: from mail-bw0-f46.google.com ([209.85.214.46]:62481 "EHLO mail-bw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751229Ab0GOUw1 (ORCPT ); Thu, 15 Jul 2010 16:52:27 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:cc:content-type; b=EjAs09INMmvUHffF/5kRDC1PmLUymKGFYxYrmqfzEw2YpCclCQtZJ+1tS4+IV4Wj2E OXLHz3pgkWtCdwtyieJYSYC9PzvoVCuLnsVQr/oALq0g1Qkn/60PMvKRBhT8XtEZ4AcV pYbrbKINJrfIHibWphSr5S/1vG0VQwtrgKBtg= MIME-Version: 1.0 In-Reply-To: <20100715200012.GA4175@brouette> References: <1279100846.8592.53.camel@e102109-lin.cambridge.arm.com> <4C3D89AC.4040303@cs.helsinki.fi> <1279205891.6664.46.camel@e102109-lin.cambridge.arm.com> <4C3F2F52.2050101@cs.helsinki.fi> <20100715162805.GA10240@brouette> <20100715191638.GA3694@brouette> <20100715200012.GA4175@brouette> Date: Thu, 15 Jul 2010 23:52:25 +0300 X-Google-Sender-Auth: rAbu1MZgK4G6gkoeq8LK-XblVkI Message-ID: Subject: Re: kmemleak, cpu usage jump out of nowhere From: Pekka Enberg To: Damien Wyart Cc: Zeno Davatz , Catalin Marinas , linux-kernel@vger.kernel.org, Andrew Morton , x86@kernel.org, mingo@elte.hu, yinghai@kernel.org, Peter Zijlstra Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2224 Lines: 42 On Thu, Jul 15, 2010 at 11:00 PM, Damien Wyart wrote: >> > For now, I can't reproduce the problem with CONFIG_NO_BOOTMEM disabled ; >> > with the option and rc5 the problem was happening quite quickly after >> > boot and normal use of the machine. So it seems I can confirme what Zeno >> > has seen and I hope this will give a hint to debug the problem. I guess >> > this has not been reported that much because many testers might not have >> > enabled CONFIG_NO_BOOTMEM... Maybe the scheduler folks could test their >> > benchmark with a kernel having this option enabled? > > * Pekka Enberg [2010-07-15 22:50]: >> To be honest, the bug is bit odd. It's related to boot-time memory >> allocator changes but yet it seems to manifest itself as a scheduling >> problem. So if you have some spare time and want to speed up the >> debugging process, please test v2.6.34 and v2.6.35-rc1 with >> CONFIG_NO_BOOTMEM and if former is good and latter is bad, try to see >> if you can identify the offending commit with "git bisect." > > Not sure I will have enough time in the coming days (doing that remotely > is fishy since ssh access is almost stuck when the problem occurs); if > Zeno can and would like to do it, maybe this could be done faster. > > As the scheduler is now very well instrumented (many debugging features > are available), reproducing the bug on a test platform (it happens quite > quickly for me) might also give some hints. So testers, if you have > time, please test 2.6.35-rc5 with CONFIG_NO_BOOTMEM on a Core i7 and see > if you can reproduce the problem! Yeah, there's "perf sched" tool available for that: http://lwn.net/Articles/353295/ The only problem is that we'd need a scheduler hacker to decipher the report and all of them seem to be missing at the moment (probably at OLS). Anyway, like I said, git bisect will probably speed up the debugging process, that's all. Pekka -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/